I do agree destruction isn't a good skill for someone not being a 'pure' dedicated mage, but the other melee combat skills are rather weak without smithing and stamina investment. This isn't about comparison though, I'm just saying how I handle destruction and make it work on master, that ISN'T 100% reduction of cost and constantly staggering the enemy.
I usually use all 6 mage skills as a mage, and from the start you can aim to get the illusion 'aspect of fear' perk which adds 10 damage to all fire spells (flames goes to 18 from 8) and the first fire +damage perk. This gives you a firebolt with around 41-43 damage, which will make you overpowered as hell even on master at the start. You don't need to do this though, I usually just level my skills naturally and still have no problems I can't deal with using tactics etc.
I recommend investing in all the element damage boosting perks (not the additional effects though, like ice paralyse as they are rather useless) as many enemies have weaknesses to specific elements. For example draugr are weak to fire, so against draugr deathlords I use incinerate that does 100 damage per shot, 220 damage dual cast, that number is then increased due to their weakness. So I'm killing these draugr deathlords in 3-4 dual casts or around 4 dual single casts (8 single casts), do consider how fast you can use spells.
The biggest problem is cost, the adept and expert spells cost way to much in my opinion, you have to use gear that reduces the cost, but not to 100% as that takes the fun away IMO, no challenge. I am for around 80-90% reduction and the perk, and I get this from 2 enchant slots and the archmage robes at the moment (necrovamp). Then I can cast a good few spells but not endlessly stagger enemies.
Being a necromage vampire boosts every enchantment you have, and pretty much everything else by x1.25, there is a link in my sig that explains it better. So with 100 enchanting and the right perks (no alchemy, just some store brought potions) I can create good enough gear to reduce all the magicka schools to around 20-40% of the cost, and have a magicka pool of around 500. You can achieve this without being a vamp, but it's easier being a necrovamp as it boosts pretty much everything. Also note that I didn't power level any skills, I started of with crappy found gear, only have stuff this good now I'm level 45-60ish, which took a while.
Knowing enemies weaknesses is a huge help, frost dragons, draugr and most undead are weak to fire, dwemer machines and dremora are weak to shock, fire dragons are weak to ice etc.
If you're obsessed with dealing insane damage, my level 60 mage can conjure a bow and fire a poison, then drink a destruction damage potion and kill an ancient dragon in a few expert level casts, dealing at least 800 damage per dual cast. Destruction is more than viable for use on master at high levels, tired of people saying how useless it is.
That's pretty much it to be honest, if people post their concerns using it I'll try to answer them.

). getting rid of the cost (and challange) gets rid of the fun of it